Vascular Calcification Markers and Hemodialysis Vascular Access Complications

Abstract

Background: Arteriovenous (AV) access dysfunction is a common complication in hemodialysis patients. Markers of vascular calcification are associated with cardiovascular outcomes and mortality in this population, but their association with vascular access outcomes is unknown. In this study, we aimed to evaluate the association between selected vascular calcification makers and vascular access complications in a cohort of hemodialysis patients. Method: Fetuin-A, osteopontin (OPN), osteoprotegerin (OPG), and bone morphogenetic protein-7 (BMP-7) were measured in blood samples from 219 dialysis patients in the Choice for Healthy Outcomes in Caring for end-stage renal disease study; these patients were using a permanent vascular access. Participants were followed for up to 1 year or until the occurrence of a vascular access intervention or replacement. Associations with AV fistula (AVF) and AV graft (AVG) intervention-free survival were assessed in models adjusted for demographic characteristics, comorbidities, and inflammation. Results: A total of 24 out 103 participants with an AVF and 43 out of 116 participants with an AVG had an intervention during follow-up. Lower fetuin-A, higher OPN, and higher BMP-7 were associated with a higher risk of AVF intervention (adjusted hazard ratios [aHR] for highest versus lowest tertile = 0.30 [95% CI 0.10–0.94]) for fetuin-A, 3.84 (95% CI 1.16–12.74) for OPN, and 3.49 (95% CI 1.16–10.52) for BMP-7. OPG was not significantly associated with the risk of AVF intervention. The associations of OPN and BMP-7 with AVF intervention appeared stronger among participants without diabetes (aHR 8.06; 95% CI 1.11–58.57 for OPN and aHR 2.55; 95% CI 1.08–6.08 for BMP-7, respectively) than among their counterparts with diabetes (p interaction = 0.06). None of the markers studied were significantly associated with AVG interventions. Conclusion: Lower fetuin-A and higher OPN and BMP-7 are associated with complications in AVF but not in AVG, suggesting a role for calcification in the pathogenesis AVF failure.